Field of the Invention
The invention relates to a semiconductor process control method and system, and more particularly, to a deposition process control method and system.
Description of Related Art
In a semiconductor process, the furnace process is an important process step. A tool for the heat treatment in the semiconductor process is, for instance, a furnace that can fabricate a structure such as a gate oxide layer or a spacer oxide layer . . . etc. of a semiconductor device via heating and oxidation.
However, fixed process parameters are used in the furnace process of the prior art, and loading effect (different deposition rates caused by total number of wafers and pattern variation on the wafers) is often neglected, thus causing different variations to film thickness formed on the wafers in the case of different placement locations of the wafers in the furnace. Such variation includes wafer-to-wafer and within-wafer variations. Moreover, various pre-process variation factors such as linewidth and film thickness all cause variation to the threshold voltage or other characteristics of the fabricated semiconductor device.
As the size of the semiconductor device continues to be smaller, the demand for the quality of the film formed by the furnace process has become greater. Therefore, the focus of the furnace process is on the thickness of deposition on the actual product and not only on the thickness of the monitor wafer. However, during production, the actual deposition thickness of each product is very difficult to sample, such that instant adjustment of optimal parameters of the process cannot be achieved. As a result, the deposition thickness of the process results is significantly deviated from the standard values.